Construction platform for building workpieces layer by layer or continuously

Abstract

The present invention relates to a construction platform (100) for constructing a workpiece (200) layer by layer in a three-dimensional printing method, the construction platform comprising: a back-side exposure device (101-1), the back-side exposure device being used to expose a layer (103-n) from the back side; a light sensor (105), the light sensor being used to detect the light intensity of the front-side exposure device (101-2) passing through the layer (103-n) and / or the material and / or passing through a deflection mirror; and a control device (107), the control device being used to activate the back-side exposure device (101-1) when the detected light intensity of the front-side exposure device (101-2) is above a predetermined extreme value.

Description

Technical Field

[0001] The invention relates to a building platform for building a workpiece layer by layer or continuously in a three-dimensional printing method, a three-dimensional printing device having a building platform and a method for building a workpiece layer by layer or continuously by means of a building platform. Background Art

[0002] Due to the absorption properties of the light-hardening materials used in the stereolithography process, the light efficiency of the mask projection is sometimes insufficient to produce sufficient adhesion of the workpiece on the building platform, which overcomes the separation forces on the bottom of the groove, so that the component remains attached on the bottom of the groove when separation is attempted. This can be achieved by actively and temporarily increasing the adhesion of the substrate layer on the building platform by means of backside exposure on the surface of the building platform.

[0003] Document EP2337667B1 relates to an apparatus for processing photopolymerizable materials. A backside exposure device integrated into the building platform is connected to the control device of the printer and is controlled by the printer control device during the building process for the first layer. Summary of the invention

[0004] The technical object of the present invention is to provide a modularly replaceable and independent building platform which operates independently of the printer control and prevents an unintentional detachment of the building platform from the built-up layers in a simple manner.

[0005] According to a first aspect, this technical task is achieved by a building platform for building a workpiece layer by layer or continuously in a three-dimensional printing method, the building platform having: a backside exposure device for exposing a layer from the back side; a light sensor for detecting the light intensity of the front-side exposure device through the layer and / or material and / or via a deflection mirror; and a control device independent of the printer for activating the back-side exposure device when the detected light intensity of the front-side exposure device is above a predetermined limit value. This achieves the following technical advantages, for example: the first layer to be built is exposed and hardened from two opposite sides and the adhesion on the building platform is improved.

[0006] According to a second aspect, this technical task is achieved by a building platform for building a workpiece layer by layer or continuously in a three-dimensional printing method, the building platform having: a backside exposure device for exposing a layer from the back side; a detection device for detecting the production of a first layer; and a control device independent of the printer for activating the backside exposure device when the production of the first layer is detected. The same technical advantages are achieved as with the building platform according to the first aspect.

[0007] The detection device can, for example, comprise a mechanical button or a distance sensor which is integrated in the building platform and is triggered in the first layer. The detection device can be designed to activate a counter which counts the number of layers built and activates the back exposure device below a predetermined value, for example for the first five layers. At the start of the building process, the building platform can be moved back onto the button. Activation can be carried out by means of near field communication (NEC) until the height is determined.

[0008] In a technically advantageous embodiment of the building platform, the rear-side exposure device is formed by a light-emitting diode array, thereby achieving, for example, the following technical advantages: large-area exposure and curing are possible with low energy consumption.

[0009] In another technically advantageous embodiment of the building platform, the light intensity or exposure time of the backside exposure device can be set by means of a voltage divider or can be controlled by an internal control device. This achieves the technical advantage that the light intensity can be controlled manually or automatically and can be adapted to the material used.

[0010] In another technically advantageous embodiment of the building platform, the number of layers exposed on the back side can be controlled by means of a counter. This achieves the following technical advantage, for example: the back side exposure only has to be triggered in the first layer if the other layers absorb too much light and no longer activate the light sensor. Even if there is too little light, further back side exposures can be additionally carried out until the predetermined number of layers is reached by the counter.

[0011] In another technically advantageous embodiment of the building platform, the building platform comprises an electrical energy storage device for storing energy for the rear-side exposure device, thereby achieving, for example, the following technical advantage: the building platform can be supplied with the required energy independently and without external connecting cables.

[0012] In another technically advantageous embodiment of the construction platform, the energy store is a rechargeable and / or replaceable accumulator, thereby achieving the technical advantage that the energy store can be reused, for example.

[0013] In another technically advantageous embodiment of the building platform, the light sensor is a photodiode, which is coordinated with the wavelength range of the front-side exposure. The photodiode is, for example, a silicon carbide photodiode or a silicon photodiode. This achieves the technical advantage that the light intensity can be determined with high accuracy.

[0014] In another technically advantageous embodiment of the building platform, the photodiode in the wavelength range of the front-side exposure device is sensitive in the UVA range or in the blue light range. This achieves the technical advantage that suitable wavelengths for curing the material can be detected.

[0015] In another technically advantageous embodiment of the building platform, the predetermined limit value for activating the rear-side exposure can be set by the user, thereby achieving the technical advantage that the limit value can be adapted to the material used.

[0016] In another technically advantageous embodiment of the building platform, the building platform can be modularly integrated into a three-dimensional printing device with the rear-side exposure device, thereby achieving the following technical advantage, for example: the building platform can be replaced.

[0017] In another technically advantageous embodiment of the building platform, the backside exposure device can be modularly mounted or pushed onto the building platform, thereby achieving technical advantages, for example, that an exposure device can be selectively inserted or replaced or an exposure device particularly suitable for the material can be used.

[0018] In another technically advantageous embodiment of the building platform, the building platform can be operated wirelessly, thereby achieving, for example, the following technical advantages: the construction and operation of the building platform are simplified.

[0019] According to a third aspect, this technical object is achieved by a three-dimensional printing device having a building platform according to the first aspect or the second aspect. The three-dimensional printing device achieves the same technical advantages as the building platform according to the first aspect.

[0020] In a technically advantageous embodiment of the 3D printing device, the 3D printing device is designed such that part of the light of the front exposure device, which is used for exposing the first layer, is directed to the light sensor and thus activates the back exposure device. This achieves the following technical advantage, for example: the back exposure is activated indirectly by the construction process / exposure process itself and does not require direct control by the printer.

[0021] According to a fourth aspect, this technical task is solved by a three-dimensional printing method for building a workpiece layer by layer or continuously by means of a building platform, the three-dimensional printing method comprising the following steps: exposing the layer from the front side by means of a front exposure device; detecting the light intensity of the light of the front exposure device through the layer and / or material and / or via a deflection mirror by means of a light sensor; and activating the back exposure device by means of a control device independent of the printer when the detected light intensity of the front exposure device is above a predetermined extreme value. The same technical advantages as those intended by the building platform according to the first aspect are achieved by means of the method.

[0022] According to the fifth aspect, this technical task is solved by a three-dimensional printing method for building a workpiece layer by layer or continuously through a construction platform, and the three-dimensional printing method has the following steps: detecting the production of a first layer by a detection device; and when the production of the first layer is detected, activating the back exposure device by a control device independent of the printer.

[0023] In a technically advantageous embodiment of the method, the backside exposure device is activated for a predetermined number of layers and / or with an adapted exposure duration per layer. This achieves the technical advantage that the degree of polymerization of the material curing on the backside can be controlled with high precision.

[0024] In another technically advantageous embodiment of the method, the height of the building platform is taken into account for the building process in order to determine the starting position of the building platform and to set a predetermined layer thickness for the layer, thereby achieving the technical advantage that the theoretical layer thickness can be maintained even when the building platform is replaced. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Exemplary embodiments of the invention are illustrated in the drawings and are described in more detail below.

[0026] In the attached figure:

[0027] Figure 1 A schematic state showing a construction platform in a stereolithography method;

[0028] Figure 2 Another schematic state of a construction platform in a stereolithography method is shown;

[0029] Figure 3 Another schematic state of a construction platform in a stereolithography method is shown; and

[0030] Figure 4 A block diagram illustrating a method for building a workpiece layer by layer or continuously. DETAILED DESCRIPTION

[0031] Figure 1 A cross-sectional view of a schematic state of a construction platform 100 in a stereo printing method is shown. The construction platform 100 is used to build a workpiece 200 layer by layer or continuously in a stereo printing method. For this purpose, the lower side of the construction platform 100 is in a viscous material 109, which can be hardened by means of light. If a layer is hardened, the construction platform moves away from the exposure plane and is fed to the subsequent layer thickness, so that the viscous material can flow in again to then harden. The material 109 is, for example, a ceramic slurry for the manufacture of dental restorations. In general, however, other materials can also be processed.

[0032] The construction platform 100 comprises a backside exposure device 101-1 for exposing a layer 103-n of material 109 from the backside. The exposure device 101-1 comprises a plurality of light emitting diodes 113, which are arranged behind a transparent surface 117. The light emitting diodes 113 can, for example, emit light with a wavelength in the range of 220 nm to 500 nm. The maximum in the spectrum can, for example, be at 365 nm, 385 nm, 405 nm or 460 nm. In general, however, other wavelengths can also be used.

[0033] By backside exposure, the material 109 hardens directly on the transparent surface 117 of the building platform 100 and forms a layer (burn-in layer) firmly attached to the building platform. This measure can prevent the workpiece from accidentally detaching from the building platform 100. The light intensity and / or exposure time of the backside exposure device 101-1 can be adjusted for each layer by means of a voltage divider, or can be automatically adapted for each layer by an internal control device.

[0034] The building platform 100 comprises an electrical energy storage device 115 for storing energy for the backside exposure device 101-1. The backside exposure device 101-1 can be independently supplied with electrical energy via this energy storage device 115, without having to lead cables into the building platform 100 for this purpose. The electrical energy storage device 115 can be, for example, a battery pack or an accumulator pack.

[0035] On the opposite side of the building platform 100, the stereolithography device 300 comprises a front exposure device 101-2. The front exposure device 101-2 comprises a digital projection unit 113, which is arranged under the transparent bottom 111. The front exposure device 101-2 is used to harden the material layer by layer through the transparent groove bottom from the opposite side of the building platform. Any light pattern can be projected onto the material by the projection unit 113. The projection unit 113 can include a digital micromirror device (DMD) or a liquid crystal display (LCD) for this purpose.

[0036] The construction platform 100 comprises a light sensor 105 which is suitable for detecting the light intensity of the light of the front exposure device 101-2 passing through the material 109. The light sensor 105 can be formed, for example, by a photodiode. The more layers the workpiece being constructed has, the smaller the light intensity detected by the light sensor 105. The light sensor 105 is positioned in a corner of the structure area (=exposure area) and can react to the exposure of the layer 103.

[0037] This effect can be used to activate the back exposure device 101-1 only for the first layer 103-n, thereby preventing unnecessary exposure of the layer that has already hardened on the transparent surface 117 on the one hand and not hardening an unnecessary number of layers on a large area and thus wasting material unnecessarily on the other hand. In addition, electrical energy is saved. For this purpose, the construction platform 100 includes an electronic control device 107, which activates the back exposure device 101-1 only when the detected light intensity of the front exposure device 101-2 is above a predetermined extreme value. The extreme value can be set to any value. Therefore, the energy storage device 115 of the construction platform 100 can be used for a longer time. If the detected light intensity is below the predetermined extreme value, that is, a certain number of layers are already present, the back exposure device 101-1 is no longer activated. In addition, the number of layers exposed on the back side can be controlled via an adjustable counter. The counter counts the number of layers constructed from the beginning. Until the predetermined number of layers constructed, the back exposure device 101-1 is activated respectively.

[0038] Figure 2 Another schematic state of the building platform 100 in a stereolithography method is shown. In this case, the first layer of the workpiece is built. A portion of the light of the front exposure device 101 - 2 passes through the material and is incident on the light sensor 105 .

[0039] The light sensor 105 detects the high light intensity of the front exposure device 101-2. Because there are only individual material layers. The light that penetrates through the material layer is only absorbed by the material layer in a small part. As the number of layers increases, the light intensity decreases accordingly. Since this light intensity is above a predetermined extreme value when the number of layers is small, the back exposure device 101-1 is activated as a reaction. Therefore, the layer is not only exposed from the front side independently of the component but also exposed from the back side over the entire surface. This forms a layer (Burn-In-layer) that is fixedly attached to the construction platform 100.

[0040] Figure 3 Another schematic state of the construction platform 100 in the stereolithography method is shown. The layer 103-n is hardened and adheres to the transparent surface 117 of the construction platform 100. Next, the construction platform 100 is lifted and another layer 103-n is built. As the number of layers 103-n increases, the detected light intensity decreases. Once the light intensity drops below a predetermined extreme value or the counter stops, the back exposure device 101-1 is released. As a result, the number and degree of polymerization of the required Burn-In layers can be accurately controlled and the service life of the accumulator 115 can not be reduced unnecessarily and the control by the printer can be omitted.

[0041] The building platform 100 may include a counter which determines how many layers should be exposed on the back side. In addition, a deflection mirror may be provided, by means of which light can be deflected from the front exposure device 101 - 2 directly onto the light sensor 105 . The building platform 100 may also include a digital storage device in which the dimensions of the building platform, for example the height, are stored as digital values. This digital value can be read by the three-dimensional printing device 300 so that the building platform with the back exposure unit can be calculated and adjusted to the desired Z value relative to the starting position (0 position) of the transparent bottom 111 .

[0042] Figure 4 A block diagram of a method for building a workpiece 200 layer by layer by means of a building platform 100 is shown. In a first step S101, a layer 103n is exposed from the front side by means of a front exposure device 101-2. In a step S102, the light intensity of the light of the front exposure device 101-2 passing through the layer 103-n and / or the material 109 and / or passing through the deflection mirror is then detected by means of a light sensor 105. In a step S103, when the detected light intensity of the front exposure device 101-2 is above a predetermined limit, the back exposure device 101-1 is activated by means of a control device 107. When the light intensity is below a predetermined limit, the back exposure device 101-1 is deactivated.

[0043] The backside exposure device 101-1 is activated for a predetermined number of layers 103-n. For this purpose, a counter can be provided, which counts the number of layers built. For the building process, the height of the building platform 100 used for the building process can be taken into account in order to determine the starting position of the building platform 100 and to set a predetermined layer thickness of the layer 103-n.

[0044] The building platform 100 with the integrated backside exposure device 101 - 1 can be equipped and operated without being electronically connected to the three-dimensional printing device 300. The backside exposure device 101 - 1 is controlled or triggered via an integrated light sensor by a standard mask exposure of the burnout layer.

[0045] The backside exposure device 101-1 is controlled via a light sensor 105, which is triggered by the exposure of the substrate layer by the frontside exposure device 101-1. The backside exposure device 101-1 can thus be controlled or connected synchronously with the mask projection.

[0046] The backside exposure is temporarily carried out for the first five layers 103 in parallel with the actual exposure of the burnt layer. Independently of the rest of the three-dimensional printing device 300 , the power supply is provided by an energy storage device 117 integrated into the building platform 100 .

[0047] By indirect control via the light sensor 105, the back exposure device 101-1 can be activated without mechanical buttons and without electrical connection to the rest of the three-dimensional printing device 300. The energy storage device 115 allows an independent energy supply for which no external cables are required.

[0048] In accordance with the standard, a 3D printing device 300, for example a 3D printing printer, is often not equipped with a building platform 100 with a backside exposure device 101-1 connected to a control device. An independent building platform 100 enables the 3D printing device 300 to be equipped without having to modify the 3D printing device in terms of hardware and / or software. The equipped building platform 100 is operated autonomously by the printer control device and is controlled / triggered during the building process only via the exposure of the front side exposure device 101-2.

[0049] All features explained and shown in conjunction with the various embodiments of the present invention may be provided in different combinations in the technical solution according to the present invention in order to simultaneously achieve their advantageous effects.

[0050] All method steps can be implemented by devices suitable for implementing the corresponding method steps. All functions mentioned in the device features can be method steps of the method.

[0051] The scope of protection of the invention is given by the claims and is not limited by the features set forth in the description or shown in the drawings.

[0052] Reference numerals list

[0053] 100 Construction Platform

[0054] 101 exposure device

[0055] 103rd floor

[0056] 105 Light Sensor

[0057] 107 Control Device

[0058] 109 Materials

[0059] 111 bottom

[0060] 113 LEDs

[0061] 115 Accumulator

[0062] 117 Transparent surface

[0063] 300 3D printing device.

Claims

1. A building platform (100) for building a workpiece (200) layer by layer or continuously in a three-dimensional printing method, the building platform comprising: A backside exposure device (101-1), the backside exposure device being used to expose the layer (103-n) from the backside; A light sensor (105) for detecting the light intensity of the light from the front exposure device (101-2) passing through the layer (103-n) and / or the material and / or passing through the deflection mirror; and A control device (107) independent of the three-dimensional printing device is used to activate the back-side exposure device (101-1) when the light intensity detected by the front-side exposure device (101-2) is above a predetermined extreme value.

2. The construction platform (100) according to claim 1, wherein: The backside exposure device (101-1) is composed of a light emitting diode array.

3. The construction platform (100) according to claim 1 or 2, wherein: The light intensity or exposure time of the backside exposure device (101-1) can be adjusted by means of a voltage divider or can be controlled by an internal control device, and / or the number of layers (103-n) exposed on the backside can be controlled by means of a counter.

4. The construction platform (100) according to claim 1 or 2, wherein: The building platform (100) comprises an electrical energy storage device (115), which is used to store energy for the back-side exposure device (101-1), and / or the energy storage device is a rechargeable and / or replaceable accumulator.

5. A construction platform according to claim 1 or 2, wherein: The light sensor (105) is a photodiode which is tuned to the wavelength range of the front-side exposure.

6. The construction platform (100) according to claim 5, wherein: In the wavelength range of the front-side exposure device, the photodiode is sensitive in the UVA range or in the blue range.

7. The construction platform (100) according to claim 1 or 2, wherein: The predetermined limit for activating the backside exposure can be set by the user.

8. The construction platform (100) according to claim 1 or 2, wherein: The construction platform (100) can be modularly embedded in the three-dimensional printing device (300) with the back-side exposure device (101-1), or the back-side exposure device (101-1) can be modularly mounted or pushed onto the construction platform (100).

9. A building platform (100) for building a workpiece (200) layer by layer or continuously in a stereolithography method, the building platform comprising: A backside exposure device (101-1), the backside exposure device being used to expose the layer (103-n) from the backside; A detection device (105), the detection device being used to detect the manufacturing of the first layer (103-1); and A control device (107) independent of the three-dimensional printing device, the control device is used to activate the backside exposure device (101-1) when the production of the first layer (103-1) is detected.

10. The construction platform (100) according to claim 9, wherein: The backside exposure device (101-1) is composed of a light emitting diode array.

11. The construction platform (100) according to claim 9 or 10, wherein: The light intensity or exposure time of the backside exposure device (101-1) can be adjusted by means of a voltage divider or can be controlled by an internal control device, and / or the number of layers (103-n) exposed on the backside can be controlled by means of a counter.

12. The construction platform (100) according to claim 9 or 10, wherein: The building platform (100) comprises an electrical energy storage device (115), which is used to store energy for the back-side exposure device (101-1), and / or the energy storage device is a rechargeable and / or replaceable accumulator.

13. The construction platform (100) according to claim 9 or 10, wherein: The construction platform (100) can be modularly embedded in the three-dimensional printing device (300) with the back-side exposure device (101-1), or the back-side exposure device (101-1) can be modularly mounted or pushed onto the construction platform (100).

14. A three-dimensional printing device (300), comprising a building platform according to any one of claims 1 to 13.

15. The three-dimensional printing device (300) according to claim 14, characterized in that: The three-dimensional printing device (300) is designed to direct a portion of the light of the front-side exposure device for exposing the first layer onto the light sensor and thus activate the back-side exposure device.

16. A three-dimensional printing method for building a workpiece (200) layer by layer or continuously in a three-dimensional printing method by means of a building platform (100), the three-dimensional printing method comprising the following steps: Exposing the layer (103-n) from the front side by a front side exposure device (101-2) (S101); Detecting (S102) the light intensity of the light from the front exposure device (101-2) passing through the layer (103-n) and / or the material and / or passing through the deflection mirror by means of a light sensor (105); and When the light intensity detected by the front-side exposure device (101-2) is above a predetermined extreme value, the back-side exposure device (101-1) is activated (S103) by a control device (107) independent of the three-dimensional printing device.

17. The three-dimensional printing method according to claim 16, wherein: The backside exposure device (101-1) is activated for a predetermined number of layers and / or with an adapted exposure duration per layer.

18. The three-dimensional printing method according to claim 16 or 17, wherein: The height of the building platform (100) is taken into account for the building process in order to determine the starting position of the building platform (100) and to set a predetermined layer thickness of the layer (103-n).

19. A three-dimensional printing method for building a workpiece (200) layer by layer or continuously by means of a building platform (100), the three-dimensional printing method comprising the following steps: Inspecting the production of the first layer by means of an inspection device (105); and When the production of the first layer is detected, the backside exposure device (101-1) is activated by a control device (107) independent of the three-dimensional printing device.

20. The three-dimensional printing method according to claim 19, wherein: The backside exposure device (101-1) is activated for a predetermined number of layers and / or with an adapted exposure duration per layer.

21. The three-dimensional printing method according to claim 19 or 20, wherein: The height of the building platform (100) is taken into account for the building process in order to determine the starting position of the building platform (100) and to set a predetermined layer thickness of the layer (103-n).

Images